1. Field of the Invention
This invention relates to a keyboard for use in an information processing device such as a word processor and computer, which is capable of readily inputting data or programs to the information processing device by keying operations and is based on human engineering, and particularly to a keyboard having key arrangement which permits keys disposed thereon to be readily operated by naturally moving the fingertips of the operator's hand in a physiological resting position on a keyboard base without the smallest strain.
2. Description of the Prior art:
Characters such as capital and small letters, numerals and marks to be used in writing a composition in English do not exceed 100. There has widely spread a universal keyboard having four rows of ten or more keys to input many kinds of key signals to an information processing device such as a word processor. Much practice is required to handle the universal keyboard with quickness and dexterity. However, even a skilled operator becomes fatigued while performing keying work for a long time, because the keying operation requires large momentum of the operator's fingers. Though the keying operation for making an English composition is performed in such a manner as noted above, the conventional universal keyboard makes it impossible to readily input language such as Japanese which has as many as at least 200 kinds of characters including kana characters, alphabets, numerals, marks, etc. necessary for making a Japanese composition.
There have been hitherto proposed a variety of keyboards capable of easily inputting a large number of key signals by operating a small number of keys. By way of example, U.S. Pat. No. 4,584,443 discloses a portable keyboard having multi-contact switches disposed opposite to the corresponding fingertips of an operator on a keyboard base. In this keyboard, the keys each have a cap-like profile so that the operator's fingers can be inserted in the cap-like keys to operate the keys.
Also in U.K. patent application Public Disclosure No. 2,076,743(A), a keyboard having curved recesses in which the operator's fingers can rest has been proposed.
Furthermore, Japanese patent application Public Disclosure SHO No. 59-140548(A) has proposed a keyboard in which adjacent keys are pressed at one time to enter a specific key signal without straining the operator's hand. And, patent application Public Disclosure SHO No. 59-98264(A) discloses a portable keyboard which can be held and handled with one hand and adopts an ergonomic key arrangement. This keyboard is small so that it can be held and operated with one hand, and is provided with five keys arranged on a keyboard proper so as to be opposite to the respective fingertips of the operator's hand.
The conventional keyboards including the aforementioned prior art are constructed for the purpose of inputting various information data with simple movements of the fingers of an operator. However none of the conventional keyboards are provided with a key arrangement based on human engineering in consideration of a physiological resting position of the hand and fingers. As is medically defined, a physiological limb state in which the muscles of the hand and fingers are completely relaxed is generally referred to as the "resting position". There has heretofore not been a keyboard which can be operated with the natural and free movements of the hand and fingers which are maintained in the physiological resting position without straining the muscles of the hand and fingers. In the physiological resting position of the hand, the fingers other than the thumb are bent inward and slightly spread out, and the thumb points to the fingertip of the index finger in such a state that the finger pad thereof is directed inward, so that the palm of the hand defines a substantially semi-spherical hollow space. With this in mind, the keyboard disclosed in U.S. Pat. No. 4,584,443 has thumb keys with thumb holes separated from the keys for the fingers other than the thumb. When the thumb is set in the thumb hole formed in the thumb key and the other fingers rest on the other keys, the thumb is forced to assume the radial abduction state in which the thumb is extended so as to be perpendicular to the other fingers. With this keyboard, the operator becomes fatigued while performing keying work because the hand and fingers cannot assume their physiological resting position. Also, none of the prior art including U.K. patent application Pub. Discl. No. 2,076,743(A), are aimed at allowing the hand and fingers during a keying operation to assume the physiological resting position and thus can in no way be said to facilitate keying work based on human engineering. Furthermore, hitherto there has not been a keyboard capable of being fitted to hands of different sizes so as to allow every different size hand to assume the physiological resting position during a keying operation.